Bad Gateway 502 on WordPress Login

Somehow the purge_post_on_update is called on the login page?! and because  $post_type_object = get_post_type_object($post_type); is null, the following condition errors out:`Somehow the purge_post_on_update is called on the login page?! and because  $post_type_object = get_post_type_object($post_type); is null, the following condition errors out:

if ((defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) || 'revision' === $post_type  || !$post_type_object->public) {
    return;
}

2023/01/17 13:41:18 [error] 746#746: *689 FastCGI sent in stderr: "PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146PHP message: PHP Warning:  Attempt to read property "public" on null in /home/vsp/xxxx.com/dist-wp/wp-content/plugins/wp-optimize/cache/class-wpo-cache-rules.php on line 146" while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: xxxx.com, request: "GET /wp-login.php?redirect_to=https%3A%2F%2Fxxxx.com%2Fwp-admin%2F&reauth=1 HTTP/1.1", upstream: "fastcgi://unix:/run/php/php8.1-fpm-vsp.sock:", host: "xxxx.com"
2023/01/17 13:41:18 [error] 746#746: *689 upstream sent too big header while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: xxxx.com, request: "GET /wp-login.php?redirect_to=https%3A%2F%2Fxxxx.com%2Fwp-admin%2F&reauth=1 HTTP/1.1", upstream: "fastcgi://unix:/run/php/php8.1-fpm-vsp.sock:", host: "xxxx.com"

The soution is to check for null in the same if

if ((defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) || 'revision' === $post_type || $post_type_object == null || !$post_type_object->public) {
    return;
}